Human Apparatus
by njckle
Summary: The Earth has been invaded by a species that take over the minds of human hosts. Hiro wants to hate the invading "soul" who's taken his brother's body, but it's harder than it looks. The Host AU.


Hiro watches the doppelganger through the fringes of his hair, eyes never straying from its face. He keeps to himself, staying silent as the refugees push the person to the ground. With a herculean effort, he keeps his breathing even and stops his fingers from twitching when more force than necessary is used.

He wants nothing more than to go forward, but he can't- he won't.

Because everything's wrong, so very wrong.

Physically, it looks like it always has, nothing out of place to the average stranger. The same, but different nonetheless. Everything that mixed and melded together to come together and make a person, gone, leaving only a shell.

 _It's the eyes_ , his mind whispers, _they're like them_. Silver, not brown. Not human. He turns away when they roam the crowd and find him.

In the end, everyone looks to him for the final word, unconsciously weighing him down with the power they're giving him. He's the youngest, the smallest, the weakest, but he's expected to handle something that's beyond him. Some of the older survivors argue against it; he's just a kid, what does he know. That dies down quickly enough (GoGo couldn't be pushed around once she'd made up her mind), smothered before it even began.

It made sense, Hiro supposes. It was his brother after all.

* * *

No one says it outright, but he knows they worry about him. Not a day goes by where he doesn't see the doppelganger (not-Tadashi who's Tadashi, but how can that be when Tadashi's dead), which settles down across from him with that familiar-yet-alien face and gives him the excuse to study it for something-anything that could give him hope.

They keep it in the deepest part of the underground structure, separated from what they deem their living quarters. Strangely enough, it's not far from Tadashi's lab.

The cell in general is dusty and dark, with only one cot and a small bathroom making it semi-livable. Today, he's sitting across from it with his knees pressed against his chest, staring at the features that once belonged to his brother. More than ten minutes have past in this manner, with an awkward air that won't go away no matter how much he wishes it would.

It isn't long until he sucks up enough courage to ask the one question that's been plaguing him. "Why are you here?"

All he's greeted with is silence, no inclination that his words have gotten through. He's never seen a face so expressionless, a sense of emptiness given off like some sort of childlike naivety.

"Why are you here?" Hiro repeats, leaning forward. "C'mon, I know you can talk."

It blinks, long and slow, taking longer than necessary. It crosses its legs and sits up straighter. "I don't understand." Chills run down Hiro's spine at the voice, so monotone and flat and quiet. He wants to leave, but he started this, so he's going to finish it.

"Why did you come here?" Again, he's given the blank stare. "You could've told the Seekers about us and left it at that, but you didn't. Now you're stuck here. Why?"

"I was… coming back."

"Yeah, but why?" he presses, wanting to make sense of the reasoning behind coming back to a place that would hate him. Robotics and quantum physics he can understand, but this is something that's beyond him.

Silence reigns as the doppelganger tilts its head to the side, contemplating the answer, its brow furrowed in an expression that Tadashi only made when he came across a problem with no easy way to explain the answer. "I... didn't know if you were alright."

"What?" Hiro's taken back, not believing he'd heard it right. It came back to check up on him? Ridiculous, he wants to say, absolutely ridiculous. What kind of answer was that?

"I said I-"

"I know what you said, that was rhetorical!" Hiro runs his hand through his hair, feeling more like a broken record. "Why?"

This time the fake purposely doesn't reply, eyes glued to the ground. It's gone from not knowing how to answer to not wanting to. A minute passes in silence and Hiro lets it.

Hiro can't find it in himself to force an answer, instead asking, "Was it worth it?"

"Yes." Brown eyes glance up (in the shadows there's no bright ring, only black), catching his own. "It was worth it..."

The conviction in the voice and the intensity of the stare- some foreign emotion somehow underlying in every word- startles Hiro. That kind of dedication wasn't possible, wasn't supposed to exist for him anymore because only-

He bolts without another word, not willing to consider what this could mean for the future.

* * *

He manages to convince GoGo (and all the others, by default) to let it roam around the base. What kind of threat would it pose to place filled with humans? Nothing, he argues, absolutely nothing.

Really, it's because he can't keep going back to the cell every day when he has work to do.

This decision turns out to be the bane of his existence. With no one else wanting to 'babysit the 'centipede' besides himself, he's stuck with watch duty (can he really complain when he sneaks glances as often as he already does?).

The glares that are directed behind him as he walks down the hallways make him uncomfortable, but he keeps his gaze straight ahead. It's not to him, he knows, but there's anger coming from every direction and he feels like he's burning under the pressure. Though the doppelgänger seems not to notice, attention usually on the back of Hiro's head rather than the sneering faces of the other inhabitants.

How strange that he's the one being followed, after years of running after Tadashi like a lost puppy.

He doesn't know how high strung he is until he snaps. His anger had been boiling, rising to the surface, all without his knowing.

When it happens, it's towards a girl who openly throws a wrench over his head. Neither he nor not-Tadashi are hurt, the girl's aim terrible in her anger, but Hiro sees the surprise flitting on the doppelgänger's face.

Before he knows what he's doing he's grabbed the wrench and thrown it back with a "How do you like it, huh?" His aim is just as terrible, but it does just the trick, making the girl freeze- as does everyone in that part of the wing. He continues to yell, using every curse and insult he knows, wanting to show everyone that he won't be pushed around any longer.

What right did they have? It's his problem, his decision, his _brother_. They could suck it up or be bitter somewhere else.

Hands pull him back by his hood and away from the girl, who has her own wall of people keeping her back. They've started an argument, a yelling war to see who can scream at the other louder.

No amount of people between them stops Hiro from raging, wrestling to get right in her face.

Then GoGo and Honey are there, asking him to calm down (for reasons he can't fathom because he isn't the one _throwing wrenches at people_ ), but he can't because he's so angry and he wants to yell some more.

He yells at them instead.

He yells and yells, screaming until his voice is hoarse. They don't deserve it, a small part of his mind reminds him, but that doesn't matter at this point. Then there are threats coming past his lips of him leaving all this behind.

It only infuriates him that they tell him to go to his room to calm down (he wanted an argument, but all he got was pacifists), like a child on time out. The pull on his jacket is back again, gently tugging him in the direction of his room, and he hates the stares that follow.

His threats aren't empty. Half of the facility wouldn't be operational if it wasn't for him; the generators would still be lying dead and the heaters would be stuttering in their effort to keep going, and he won't even talk about the work he put into keeping the place invisible by satellites.

If he left, there'd be no hope for anyone.

But he couldn't leave even if he wanted to- where would he go?- so maybe his threats are empty. That makes him angrier.

The next moment, he's at his room, kicking his door open. His most recent project shatters when it hits the ground, tools and bolts raining down on the floor.

Hiro takes a deep breathe, trying to gather his wits together. Why was he so angry? His temper had never been a problem before, but now he could barely keep it in check. It had started when Tadashi had-

The sound of someone moving has him spinning on his heel, ready to demand they leave him alone. Maybe _he'd_ be the first to throw a wrench.

Not-Tadashi stands at the doorway, staring at him with wide eyes.

"What?" Hiro snaps, hands balling into fists. He'd rather have anger over sadness any day, so he's not really appreciative of being followed- of the biting memories that come with seeing this face, far too ready to unearth those vulnerable feelings hiding behind the anger. "What do you want?"

Like always, all he gets is a silent stare.

For whatever reason, he can't accept that today.

"Say something will you!"

The fake looks at him helplessly, a far cry from Tadashi. Never before has Hiro been able to see how completely different the two are, angry that he'd been fooled- too weak to see past it's facade of lies and fake hopes- all because of its looks.

He turns away, disgusted. "Unbelievable." No hint of the tough, nagging brother he'd had. Maybe it never existed to begin with.

He doesn't bother to say anything when it follows him further into his room because even though he's a complete mess right now, he's more than sure it wouldn't hurt him. It was weak, non-threatening, an all out problem.

"This isn't... what I- Tadashi would want."

Hiro freezes, stops breathing entirely.

Oh no, no, no, no… it didn't just-

"Get out." The words somehow get through his clenched teeth. He rounds on the imposter, eyes wide and chest tight. "Get out! Out!"

Startled, it shies away from his punches, backing as he pushes and hits. It stumbles as he shoves it to the door, almost tripping over his broken project, but he doesn't stop. "Get out, get out, _get out!_ "

He slams the door in its face, not wanting to see it any longer, and everything quiets. It's unnatural, the silence- stifling in how it presses down on him. He's only aware of how heavily he's breathing when his breath hitches, catching in his throat; the sound is incredibly loud in his ears, yet it's not the same loud like his yelling. Whatever the difference is, it shatters the imaginary wall holding the emotions he didn't know he was pushing back.

Why did he do that?

Unable to stay standing, he slides to the floor, curling into himself; he thought his meltdown was over, but he feels his eyes begging to water.

Everyone had been expecting it, right? He'd finally shown them that he wasn't as stable and fine as he'd presented himself to be. A kid in way over his head.

With the evaluation of his recent actions comes the the little voice in his head telling him that he just made some big mistakes. He pulls at his hair, shaking his head in an attempt to forget the last hour, but it replays again and again. Every word, every insult, every threat, it comes back to haunt him.

The imposter's face pops up and Hiro doesn't want to think about how he'd never talked that way to Tadashi- not ever. _It's not him_ , he refutes, _it took him away- it deserves to be hated_.

None of his reasoning can explain why he defended it, why he said what he did, why he's like this now. That's where it all started, hadn't it? Defending the fake, the imposter, his brother's murderer.

Nothing made sense.

It's only after his tears on his cheeks are dry that he crawls into a bed that distantly smells of oil and fried circuit boards. He closes his heavy eyes, nose sniffling, and tries to escape into his own world. A world where older brothers keep their promises and never leave.

* * *

No one bothers him in the hallway after that.

* * *

The next time he lays eyes on it three days later, his brother's face is battered.

GoGo stands over a moaning body, fury edged in every line of her face. She doesn't seem to mind how close she's standing to the alien species that ruined her whole life, even having her back to it. Then there's Honey Lemon helping it stand, finding no qualms about touching it.

The blood dripping on the ground has Hiro beside them immediately.

"This _idiot_ thought he was above the rules!" GoGo rants, pushing the guy away when he finally stands. "Thinks he can just waltz in here and take care of our 'infestation problem.'"

The commotion that had Hiro and a few others running here is explained, GoGo shoving their attacker into the restraining grip of two women. Maybe the guy knows he's in trouble, maybe he doesn't, but he's over his earlier pain and struggling again.

A quickly scuffle and the man breaks free and lurches forward.

GoGo shoves Hiro back just as someone else grabs his arm and he's tumbling back into a body. One clean punch from GoGo has the guy out for the count, the refugees catching him before his falls.

Honey goes to check the guy. "I think you might have broken his nose, GoGo." A snort from her friend shows just how much that bothers her. She tells the others to put the guy in his own cell.

As the man's carried out, not-Tadashi's hand still has a firm grip on Hiro's arm.

Hiro insists that he be the one to patch it up. No offense to anyone else, but he doesn't know who he can trust with the creature anymore, not with possible killings just around the corner. They can't deal with another situation like this, so it's best to take every precaution. GoGo ends up guarding the door as he works while Honey Lemon leaves to ensure peace in the facility.

The doppelgänger is silent as he deals with its cuts (there's no attempt at mimicking his brother, not after his earlier reaction, which is a relief), watching him like usual. For once, Hiro's fine with it, as it gives him a reason to focus on his hands; nonetheless, he's rushing through everything to prevent any kind of interaction.

"You wrapped it wrong."

Hiro jerks his head up. "What?"

He realizes his mistake too late, fully taking in the fake's face. There's a lot of blood, dried and rust-colored streams around its nose down to its chin; the bruises starting to bloom on its cheekbones and temple add more color, contrasting with the red. He suspects a cut lip, but it's too hard to tell with the blood.

"My hand," Hiro lets the hand slip from his fingers as it pulls back. "It won't heal correctly with this bandaging. The-"

For whatever reason, not-Tadashi stops, tilting its head in a manner that Hiro's learned to associate with it. It stares at its hand, then at Hiro, before settling back on its hand. Hiro watches unbelievingly as it tests out his fingers, doing the same with its other hand.

It's so enthralled by its joints that it doesn't notice GoGo stare from the door.

When it finally notices, it stops. "I can do it myself if it's too much trouble."

Hiro pulls the hand back onto his lap, muttering under his breath as he unwraps. He's a genius, not a doctor. This time around, he does what the imposter tells him, wrapping in an eight pattern.

"So… GoGo told me you got to your… uh, room okay. Completely fine, in fact. No one stopped you or anything- you walked there all by yourself." From his peripheral vision, he sees GoGo nod from her spot.

The fake notices their shared look and appears confused. "Did I do something wrong?"

"No- yes, yes something's definitely wrong here." Hurt flashes across its face and Hiro has to swallow his own- the expression is far too similar to the one his brother wore when they had first felt the effects of the invasion: the day their aunt had stopped being their aunt. "You had a chance to escape, you know that right?"

It's still confused. "Why would I leave?"

"Why would y-" Hiro sputters, crushing its hand, only to quickly release it when the face winces. "Sorry! What do you mean 'why would I leave?' Why wouldn't you?"

"You're here." Hiro's reminded of his first conversation and how the honesty that was there is here now.

He lets out a laugh, one that's more self deprecating than joyous. "Yeah, well, I'm not a good enough reason to stay."

There's silence and then, "Would you want me to leave?"

Hiro opens his mouth to retort that that wasn't the question, but stops himself short. It's a question he used to think he knew the answer to, but now… he's not so sure anymore.

And even if he did, GoGo was still in hearing range. Rather than stare at the fake, he focuses on his shoes.

"Would you want to leave?"

Hiro doesn't expect the question (but he definitely knows where it's coming from). He's all too aware of GoGo's presence behind him now, listening in on his every word. "No…"

Not-Tadashi nods. "Then I'm staying." Whatever attempt at a smile is stopped with another wince.

Right, Hiro still had the face to deal with. _No more fraternizing with the enemy_ , he tells himself, focusing on its face. The cut on its lip has stopped bleeding, the same going for its nosebleed. Soon enough Hiro's finished with his work, it being more or less adequate.

To waste time, he puts all the supplies back with ultimate care and precision (Wasabi would've been proud, if he were still him). When that's done, he's left with nothing to do but to look at his 'patient.' Again, it's a mistake, but one he can't help make because the eyes are right there and he can't look away.

"Thank you," it says and Hiro wants to cry. The words are sincere and tug at his heartstrings.

 _Oh no_ , Hiro thinks, knowing exactly what's happening, _no, please don't..._

Before the invasion, he'd won every single bot fight, conquered any opponent he was pitted against. But now, with those two words, he knows he's lost. He cares, cares so much that it's sickening he even tried to think he ever did otherwise.

He realizes he's been staring long enough to look like an idiot, so he awkwardly clears his throat. "I'll, uh, ask Honey to bring you some new clothes since yours are, uh… dirty…"

He walks out of the room with his remaining dignity, not even offering Gogo a goodbye, wondering how much more complicated the situation could get.

* * *

In the following days he comes to realize that he's his worst enemy.

After much debate, it's decided that not-Tadashi would be allowed to roam free outside with constant surveillance. They can't go far, obviously, but Hiro knows how horrible it is being cooped up, the thick walls feeling like they're closing in.

It's never enough time, Hiro finding that it goes by far too fast. He's enjoying it against his better judgement, this time with doppelgänger. It feels like he's gotten something back, something he thought he lost.

Everyday, GoGo finds them, indicating that their time outside is over.

Today is no different.

Hiro wants to refute (like he does every time), to argue that it's not too late and really, no one will care if their 'prisoner' settles in for the night somewhere other than his 'cell,' but something stops him.

His body freezes when a weight presses down on his shoulder, barely lingering, but he feels the warmth through his shirt all the same. There's a second where he's back in his room, a familiar voice reassuring to _relax, you'll get it eventually_. He blinks and it's gone, the hand carelessly sliding down his arm, and he's fighting to breathe when he sees silver eyes staring down at him with an apologetic gaze. No words are spoken, the imposter taking his leave without complaint.

Then Hiro and GoGo are alone.

Shaking fingers reach to touch his own shoulder, marveling at the fact that something so simple affected him so. It shouldn't have been a big deal- except it is and he knows why, knows he can't stop himself from waiting for the next time.

Of course there's going to be a next time. He's lost all control of the situation, unable to stop. It's all gone too far, falling into the deep end without any possibility of resurfacing.

In no time flat, GoGo's crossing the distance between them; her arms are enveloping him in a snug hug even before the first sniffles come through, the way she squeezes him to her chest indiscreetly telling him that she's in the same predicament.

"I don't know what to do anymore," he complains into her shirt, hopelessly wishing it was someone else's, swallowing the sudden lump in his throat. "Why does it have to be so hard?"

GoGo doesn't offer any help, just gripping his shoulders tighter, while he silently dampens her shirt. Then Honey Lemon's there, whispering, "Everything will turn out right, just wait," and then gently urging him get some rest.

He goes to his bed wishing to hear the usual breathing of a body across the room.

* * *

More often than not, he starts to catch strange mishaps- small, insignificant things- that set his gut twisting. Habits die hard, the body-snatchers unable to erase the quirks that made them all human.

Like the way Tadashi's small smile plays on his lips, always out of view of everyone else but directed at him almost hesitantly. Or how he so obviously enjoys the sunrise, eyes content during the times he's able to catch it (Tadashi had always been an early riser for the same reason). Hiro doesn't know if the imposter is purposely doing it, but he not-so-guiltily doesn't want the favored attention to stop.

(That changes completely with the talk of his 'pubescent mood swings.' During those moments- always in the view of the public- Hiro wants nothing else than to run from not-Tadashi and hide away in embarrassment. The number of times he had to argue that _no, he wasn't nervous about flowering into his manhood_ was downright ridiculous.)

And there are the times where he catches the unconscious pat of the head, only to realize that there's no baseball cap to fix (it lies untouched in his room); not once does the fake ask for the headwear and Hiro doesn't know what to make of that. Not-Tadashi is almost Tadashi then because he never once forgot about it.

Then there's the "oh no" that he thinks he mishears on the few occasions. He's more than sure he heard it the time GoGo caught them past curfew the other day. Not to mention the playful grin that graces his lips when not-Tadashi good-naturedly accepts her order to head to their rooms and sleep before she _makes_ them, which is so reminiscence of his brother that it leaves the girl honestly stunned, flushing and spluttering before she storms away.

 _Something's changing_ , he tells himself, _he's not like the others_.

Or maybe he's finally seeing what's been there the whole time.

* * *

He finds not-Tadashi in his brother's workroom only once. He almost kicks him out in a fit of anger, but he wasn't doing anything, only standing there in front of a pudgy-looking contraption.

Not having stepped in the room for a little more than a month, he treads carefully, not wanting to disrupt anything. An invisible force is pushing down on him as he gets ever closer to the center of the room and he barely has the strength to force his breathing to stay normal.

Only, when he reaches the contraption, his hesitation leaves him in an instant, replaced by curiosity as he fully takes in the machinery. The humanoid shape is obvious, but the deflated skin of it gives him the idea that the overall look was supposed to be rounder, marshmallow-like. He reaches out and strokes the material, eyebrows raising at the realization that it's vinyl. Just as he's questioning what on Earth the robot was for, he's jolted out of his thoughts.

"Baymax." When Hiro looks behind him, Not-Tadashi is looking at him with a serious expression. "This was Baymax."

"Baymax?" Never once had he heard about the project, his brother not speaking a word to him. Questions start popping into his head, but eventually die out with the knowledge that, with the absence of his brother, he would never know for sure. The sight of the robot puts a smile on his face, wondering just what his brother thinking when designing it. Very nonthreatening and huggable, a design that his brother's gentle name was written all over.

"Killer actuators," he murmurs, moving closer for a better look. Pushing aside some of the fabric, he peeks at the inner workings of the robot, mind whirling with ideas. His brother put some serious time and work into the project, some of the parts almost extinct (considered medieval to the eyes of their advanced conquerors). They could use these, he thinks, with the generators-

He stops, pulling his hand back like he'd been closing to petting a viper. One step, then another, and he's clear of the project, away from the reminder of what he lost, of what he was about to do. This was his brother's project and he had just been considering dismantling it.

What was _wrong_ with him?

"Hiro?"

Again, he's shaken out of his thoughts, jerking back at the light touch on his shoulder. There's guilt when he sees the concerned expression morph into hurt, but he's too mortified to apologize.

"D-Don't," he stutters as not-Tadashi reaches for him again, "just... don't."

The eyes stare at him again, always with the same patience that he doesn't deserve. His mind goes back to the first time they spoke, the reason behind it all and the conviction, and he knows he can't handle any more of this by himself.

His feet are moving, leading him away from the doppelgänger, who's watching him from beside his brother's project (the image looks far too _real_ ). He turns and runs, not wanting to face them any longer.

"Hiro!"

* * *

His little freak out isn't brought up, not-Tadashi only smiling in relief the next time he sees him. It's gone in an instant as Hiro tells him he won't be around for a few days.

"But you are only fourteen," not-Tadashi presses, eyes wide and displaying concern. Hiro looks away, instead busying himself with his pack. "You could get hurt."

"So," he says, rechecking his supplies, "I've done it before. No biggy." And he has, scavenging for parts to keep the place running; there might be former SFIT students in the midst, but he's by far the best. There isn't a reason he shouldn't go.

The fake sighs and Hiro can't help but think that Tadashi had been that exasperated whenever he snuck out, always with grudging acceptance. Hiro stares longer than he needs to when not-Tadashi rubs his face ( _oh, what would mom and dad say?_ ) "Exercise some caution... please."

And so he promises-

-and his mind wanders to the nights spent on the back of a bike, hands fisted in a familiar cardigan and the overwhelming feeling of safety takes over. It's strange how different this all is from before the invasion, his brother never the one to allow him to go into dangerous territory, much less with the knowledge that he might not came back. Then again, nothing about them is normal now, nor will it ever be the same.

He's still trying to figure out whether he's fine with that.

* * *

Morning's just beyond the horizon when the Seekers are spotted.

There's a call through the group, alarm spreading through like the plague; fear follows suit, spurring them on. All too soon he's being pushed, shoved, and dragged in the rising panic.

The pill in his pocket suddenly feels heavy, slowing him down as the others rush by. His legs and chest start to burn and soon enough he's out of breath, his smaller frame unable to keep up with the impossible pace.

The pill, he has a pill- _last resort_ , he chants, _last resort, last resort, last resort last-_

The strap of his backpack digs at him painfully, pulling him away from freedom as the Seekers snatch him; unfamiliar hands grab him, their touch seeing his pulse racing. None of the others look back at his cry and none of them stop when he calls out.

The pill-

-his last resort, he needed to get it out, needed to take it now before-

He coughs and tries to twist away when something is sprayed in his face, the scent of grape overwhelming. _Game over_ his body screams at him, failing under the immediate effects of the spray (an aerosol drug, surely).

It's like his body looses all coordination, his brain slowly following suit; no matter how hard he tries, nothing will follow his commands. Still, he resists, pushing away anymore of the strange-smelling spray away from him, kicking any shins or any body part that comes close. He breaks free after a particularly successful kick, bolting the moment he can.

He doesn't get far, tripping over his own feet before a body rams into him and knocks him to the ground. The weight is crushing, hands gripping his forearms painfully, making him wince. Words fly right over his head, 'violent human' and 'subdue him' the most prominent.

Someone steps on his finger. "Ow!"

Then the weight is suddenly off him and Hiro can breathe again, taking great, gasping gulps of air. His head is still in its haze and his whole body feels like it's gone numb, unable to do anything but lay there. Somehow he gets his hand in his pocket, frantic, only for his stomach to drop at the horrible realization.

His pill isn't there.

No... the Seekers... he couldn't let them-

He fingers dig into the cracks of the gravel, pulling his body forward, away from his attackers. Where was it?

Just as despair starts taking over, he sees it lying innocently not three feet away. Three- no, four feet- however far, it didn't matter, he'd get to it. With renewed will, he crawls toward it, his heartbeat loud in his ears.

Someone pulls him back just as his fingertips touch it and he wants to cry- so close, he was so close. He's spun around and patted down almost frantically, a hand finally making its way to his cheek while the other holds him close.

Wait, Seekers didn't-

"-Hiro? Are you alright, Hiro?"

He blinks his eyes open (when did he close them?), trying to focus on the blurry figure hovering over him. As his vision clears, his heart rate calms and, for a moment, he can't believe who he's seeing. "Tadashi?"

Brown eyes are the first thing he identifies and Hiro hears and feels the sigh against his forehead. It has to be his brother, no one else would-

He can't do much when he's yanked forward and squished into a chest, his arms constricted to his sides while his face is pressed into the dip between the neck and shoulders. The warmth of another body seeps into him, heating his numb limbs, his heartbeat slowly synchronizing with the steady beat in his ear.

The adrenaline from before disappears, leaving him drained and lethargic. It finally dawns on him what he was about to do, what it could've meant. A shaky breath escapes him as he clutches at whatever is put in front of him with awkward fingers.

He was about to end it right than and there. He was about to use the pill. He was about to-

A hiccup shakes him, the sound of sniffling reaching his ears. The arms around him tighten, pressing him closer, but that's fine- it reminds him of a time before the invasion.

It's all over too quickly, not-Tadashi releasing him before looking around. Hiro must be totally out of it because for a split second he thinks it's truly and fully his brother in front of him; silver vanishes in the dark and brown eyes almost looks black. "We have to go..."

"My backpack..." He wasn't going to leave it, not with all the trouble he went through for the parts. If he tilts his head just so, he can see it lying next to the… motionless figures.

He was more than sure there were more than three Seekers, so how did-

Hiro's caught staring, his brother's face looking sheepish. "I took care of them." There's a pause. "They aren't dead."

He's gently laid on the ground once more, if only for a second (but it feels like hours), before the person is back, lugging his pack like it wasn't filled to the bring with bulky parts and new tools.

Arms lift him up with ease (he can't count how many times he has fallen asleep at his desk and woken up in bed), supporting his knees and upper back. There's a moment where he wants to argue that he can walk, but a wave of dizziness hits him and he closes his eyes again with a soft groan. The world spins, his only anchor being the body next to him. He'll argue another time, he vows, but for right now he's completely fine with being taken care of.

Then they're on their way, his brother leaving the unconscious Seekers behind them. The thought seems wrong the moment he thinks it- _brother_ , he couldn't say that, could he?- and he struggles past the dizziness to figure out why.

Tadashi was...

He must've mumbled it aloud because there's a deep vibration against his ear. "I'm here."

Hiro grabs a fistful of shirt, not knowing what else to do, what to say, and listens to the pounding of the heartbeat in his ear.

Never before has something sounded so _alive_.

* * *

Somehow, the anger slowly disappears and people start to become… accepting. There's no friendliness- it's too early for that- but it's a start.

All it took was for Hiro to play damsel-in-distress apparently.

Hiro can't remember most of what happened, his memory too foggy when he tries to recall the time immediately after being saved. From the bits and pieces he's forced out of Honey Lemon and GoGo, Hiro has no doubt that his attachment to the imposter is now known among the all the refugees. Even more embarrassing, it went both ways: not-Tadashi was adamantly against letting him out of his arms, much less out of his sight, when he had stumbled back into the underground home amidst surprised faces and leveled guns.

It explains why Hiro woke up in his own bed with the imposter asleep in a chair near by.

He doesn't tell anyone that his initial thought was that it was really Tadashi sleeping there, hand limp where it laid on the bed. And he certainly doesn't tell anyone how he had grabbed the larger hand with his own, needing to know that it was real, that the person beside him was real.

Instead, he uses this newfound tolerance to better the situation; an idea has been forming some time now and there's no better moment to test it. He gets GoGo to okay not-Tadashi joining their savaging (how can she refuse when the imposter had come willingly back to them) and proceeds to go right under the Seekers noses.

What Soul would be suspicious of another?

Supplies are easier to get, no need to sneak around when they can openly take it from the stores (a few refugees agree with GoGo that it 'brings out all the fun'). Even medicine isn't a problem (not-Tadashi seems to know far more about their health than they do).

There's never any talk of how their hated prisoner becomes their most important ally.

* * *

If he can say anything about Seekers it's that they're persistent.

Their base is discovered in a moment of chaos and disorder. Once the warning reaches the main crowd, gunshots are heard coming from the entrance, echoing through the hallways.

A wave of silence passes over everyone frozen until something shatters, people dropping everything and bolting. There's no time because the Seekers were _there_ , invading their home a second time; any kind of hesitation would get them captured, taken, and replaced- killed. Hiro is reminded of Fred and how the last time he had seen him, it was a predicament not unlike this.

Not-Tadashi's grip on Hiro is painful, his nails digging into his jacket. Hiro's pulled along, jostled and off balanced by the crowd, but one look at fake's panicked face has him stopping in his tracks.

Without thinking, he turns.

"Hiro, no!"

He's pulled back to face alien eyes, wide and scared and caring. They're staring at him and Hiro can't tell what the imposter's trying to convey. He shakes his head, ripping his hand out of the loosened grip.

He's running towards the gunshots, against the flow of bodies, with only one thing in mind.

No Seekers pop out from darkened corners and Hiro makes it to his room with no problem. It's dark, but he knows the way to his desk, where the baseball hat resides. He grabs it and is out of the room without any glance at his other personal belongings (nothing else matters in comparison).

Just as he's turned a corner, a gunshot nearly deafens him. The Seekers were closing in.

The boy ducks a corner, pressing himself flat against the walls. More yelling and gunshots have him quickening his pace.

He lunges for the safety of a small, hidden alcove. He's nearly pushed back out into the chaos by a pair of hands and has to fight them in order to stay within the shelter of the shadows. The person bites him on the forearm and he hisses, "H-hey, stop it, will you!"

The struggle comes to an abrupt stop and Hiro has the time to lean back, recognizing his attacker in the dull light. It's the girl who threw the wrench at not-Tadashi his second day (Hiro ends up pushing her once more once he finally identifies her, feigning ignorance when she growls).

They stop squabbling when they hear footsteps, going deadly silent when they see a shadow sprint past them and down the hallway. Hiro hurriedly shoves himself deeper in the alcove, ignoring the girl's angry noise when her blonde head hits the wall.

"How many are there?" she asks him, voice a heavy whisper.

His shoulder bumps against hers as he shrugs, breathing back an "I don't know." Wordless, he shoves the cap onto his head.

They both jerk at the shots. Hiro doesn't push the girl away when she grabs his jacket and she doesn't say anything when he finds her hand.

And that's how the Seekers find them. Two scared kids clutching each other in the dark.

Wrench Girl screams and Hiro can't stop himself from joining her. The Seekers speak in soft tones, trying to calm and reassure even as they force their way closer. One gets close enough the make a grab at the girl, just missing her as she presses further against the wall, and rips the hat off his head instead. It makes Hiro yell louder, throwing himself against their hold.

There's something satisfying about being dragged out. It means he resisted, that he gave it his all, that he fought; if they take him, they'll take him forcefully and with problems the entire way.

It doesn't come to that as Hiro falls to the floor, painfully landing on his shoulder. Someone stands before him and his captors, familiar shoulders blocking him from view.

His replacement brother, come to save him again.

Not-Tadashi knocks two Seekers onto their backs; Hiro suddenly remembers that, with all those karate classes, Tadashi had never been completely defenseless. Another goes down with a solid punch in the temple, caught off by the silver eyes in their attacker. Wrench Girl is out of the Seekers' clutches and pushed toward Hiro. "Go!"

Hiro hesitates, stepping forward to do what, he doesn't know.

The baseball cap is shoved into his hands and he's hugged- short and awkward but better than any hug he's been given from anyone else. Another push, this time harder and more urgent. "Go! I'll be right behind you."

Fear takes over and makes the decision for him, the inner coward within having him nod weakly while clutching the cap tighter.

He grabs the girl and turns tails, needing no more encouragement. They know the way out and it's clear as long as the Seekers are behind them.

He doesn't look back.

He doesn't stop either, running as fast as his legs can take him, his lungs close to bursting. Only when his home is far behind him does breakdown. By then an expanse of trees and abandoned buildings lies between him and everything he knew since the end of his world.

The adrenaline high fades and all he can do is catch his breath on the chilled air of the night. Bracing on his knees, he feels the ache beginning take over his body, a fire burning his insides and warming his cheeks and neck as goosebumps race across his skin.

He catches Wrench Girl staring at him, then at their home. The 'told you so' tastes too much like bile for Hiro to force the words out, so he swallows it down. He doesn't say anything as he guides them to a tree and pushes her up it, following immediately after. The bark is rough against the palms of his hands, rubbing it almost raw as they clutch the trunk and settle in for the night.

It's cold and the surrounding bushes shift and whisper, but they are safe. Though neither of them sleep.

Not-Tadashi isn't anywhere to be seen.

They're found by Honey Lemon early next morning. The tall girl crushes Hiro into her chest, babbling in Spanish, but he finds he can't respond properly. He can't be relieved, or happy for that matter; his brain is dead and body just a hollow shell.

The farther away they get from their home the emptier he feels.

Hiro's searches through the crowd when they regroup, pushing through the hugging bodies and sliding past happy reunions. Worry has been building in his stomach, the feeling starting to turn into fear when his searching gives no sign of a familiar face. Honey, GoGo, and Wrench Girl offer to search, though none of them look hopeful.

He knows, but that doesn't stop him from _hoping_.

None of the other humans seem to notice or care that they're missing one person.

The baseball cap in his hands laughs at him, mocking him and his poor choice- what was a memento to living person? Hiro stands in the midst of humans- his own species-, but never has he felt more alone.

* * *

The moment he realizes his biggest mistake, Hiro finds himself standing in front of the rejected-looking project with his brother's face staring back at him from the confines of the screen.

Hiro's crying by the first sentence.

Abandonment has left the wiring faulty, the quality of the video random at best. Despite this, he gets the gist of what his brother has done.

Created an artificial Soul from his discarded robotics project.

Hiro finds it almost ridiculous, impossible even. Nonetheless, he can't bring himself to discard the idea, the possibility of something that could bring a chaotic world closer together, because this is Tadashi he's talking about. If anyone could create something so incredibly _good_ , all for a better world, it's his brother.

He thinks of all that good intent and then the previous weeks, and all Hiro wants to do is wallow in regret and self pity.

" _There are risks obviously…_ " Here, his brother looks worried, before nodding determinedly. Hiro's lucky that this part of the video remains, his brother's face so clear that he's touching his fingers to the screen. " _But, if this works, it could help a lot of people. We can't keep living like this._ "

An artificial Soul, one with no emotions or personality. Baymax was totally blank, only filled with over a thousand medical procedures- nothing else. _A clean slate_ , Hiro thinks, _that someone could imprint on_.

Everything would be new. There could be memories and feelings and opinions, but everything would be like the first time. A man-made Soul.

There is only one portion of the feed that Hiro finds difficult to watch. In it, his brother's face is haggard and drawn, looking as if he has been carrying the weight of the world and is now bending under the pressure. " _It's been… almost two months since the invasion and Hiro's decided to join the scavenging crew."_ A hand goes to wipe his tired eyes, trailing down until rubs against the short stubble growing along his jaw. " _He didn't listen when I said it wasn't such a good idea. That's not a surprise since he's so stubborn sometimes, ugh- and I still haven't even fixed the bug in Baymax. I still need to replicate his attachment to the spinal cord, which is all but impossible unless I test it out on a human subject. But who am I kidding, no one's going to volunteer and I-"_

His brother's face goes blank, reminding him of not-Tadashi and it's so weird that Hiro feels his eyebrow furrow. But the scene changes so quickly that Hiro doesn't have time to dwell on it.

The older Hamada is urgently shuffling through a stack of papers, clean shaven and presentable like always. He's muttering to himself.

" _I'll have to be quick before they- before Hiro notices I'm gone."_ His knapsack is filled with spare parts and notes and a medical kit. " _Only got one chance to make it work- oh god, I'm crazy and I'm going to die- no, stop that, you'll do fine and be fine and be safely back here in no time flat."_ Hair is mussed up, his brother having a wild look in his eyes as he tries to calm himself. Though he lets out an even breath once he looks to the lens- staring indirectly at Hiro. " _No, you're right, buddy, everything will turn out just fine. The artificial Soul will take and I'll be good and everything will turn out for the best. Yeah, you'll see. Hiro will love you- he already loves me and it'll be the same, er, sorta..."_ Eyes grow sad suddenly and there's a deep sigh. " _Hiro's going to be so angry with me, but, hopefully he'll understand. I hope he understands..."_

Hiro draws in a short breath, eyes shining with both tears and understanding. God, his brother was just too good- using himself as a test subject for an experiment that had the chance to help the world- help Hiro.

There's a flash of static and then Tadashi's smiling. " _I can't wait to show Hiro. I'm more than positive he would love Baymax, but now..."_ The laugh that follows after is so light and pure that it has Hiro smiling as he wipes his cheeks. " _He's going to freak. I'll finally be able to surprise the knucklehead, so that's a win all on it's own._ "

The video freezes, perfectly capturing Tadashi's happy expression, and Hiro's left in a silent, empty room. Above him, the robotics project stares with empty eyes, silently telling him a story about a robot who gained a soul.

Wouldn't a project made for good adopt its creator's thinking, his morals, his everything?

How far would that go?

With one look at his brother's smiling face, Hiro's out the door, fully intent on bringing back the one family he has left.

* * *

When he's alone, GoGo's tells him what she think of it all. "This is crazy."

He doesn't say anything, or else show her that he's just as unsure about his plan; he's definitely not in the right of mind to attempt a break-in into an alien-infested facility just for one measly artificial Soul. Though she's right in its insanity, he's gone over every possible course of action and there's a small chance- it's slight, but he's willing to work with whatever he's got.

Nothing she can say could change his mind.

"They'll figure out he's not one of them," he argues, stuffing his supplies with more force than necessary to hide his shaking hands because _what if he was too late_? "The first time was a fluke and now they know what Tadashi did- what Baymax is- what they are. I'm not losing anyone else, whether they're human, alien, robot, o-or-"

"Let me finish." GoGo gives him a small shove, slinging her own pack over her shoulder. "It's crazy for you to go _alone_. Tadashi was my friend, too, and he wouldn't want his little brother going in without backup. Everyone else is waiting at the entrance, so c'mon."

Relief washes over him, the knot in his chest loosening slightly, and GoGo offers him a rare smile before heading for the door.

* * *

Barely any resistance opposes them on their rescue mission, the few Souls awake this late into the night knocked out with ease that only comes with GoGo leading. They barricade the room and set up a lookout.

His brother's sleeping form is all that catches his attention, laid out so precisely on a steel table, the entirely of it all- the white walls, the empty hallways, the rows of tanks meticulously laid out- looks like it came straight out of a sci-fi film. In no time time at all, they barricade the room and gather around the table.

"Tadashi," Hiro says, shaking his shoulder, only to get no response. He tries again, shaking more forcefully. "Tadashi! B-Baymax! Ow. _Ow_."

His brother lies silent, only his rising chest to show he's alive.

Realization kicks in and one look to the back of the neck reveals the faint line barely the size of his palm. No Soul, no Tadashi, no Baymax, just an empty body.

"He's in one of the tanks."

After a few minutes of searching with no results, fear starts to build in Hiro's chest. All the tanks look the same and the Souls inside even more so. How were they supposed to find his brother?

Honey puts his anxiety to rest. "You said he was different, right Hiro? Well, what if he's separated from the rest. Either he's here or set aside somewhere."

GoGo nods. "If he's here he's going to be the odd-ball out." She turns to the two other refugees, pointing at the door across the room. "Check and see if there's more."

There's more searching, but it's hurried. They can't stay here long. A call goes out from the other room. They might have found something.

In the corner, hidden behind two tanks, is a small, circular case just as sleek-looking. Hiro immediately knows it's the Soul they're looking for, the metal cool to the touch when he grabs it.

Everyone crowds around him for a look at the Soul, finding a bright, dainty creature laying without a care in the world. After gazing at it for however long, Honey closes the case, smiling at Hiro. "Take care of him, Hiro.."

He suddenly becomes all too aware of the life in his hands, so defenseless and fragile; the empty shell that is his brother's body lying next to him doesn't come close to representing what's inside the case. Never before has he ever cared to consider the aspect of a soul, or even what makes them human (it was all axiom nerves and brain activity to him), but, if anything, the creature sealed away in his lap is everything and more.

He curls around the small tank protectively, clutching it closer to his chest. Never again was he going to let his family slip away from him- not without a fight at least.

* * *

In the end, it's all about waiting.

The others hold their breath, leaning forward for a closer look at Tadashi's face. While everyone else keeps a few feet (Hiro catches the eye of Wrench Girl, who waves awkwardly though sincerely), GoGo and Honey Lemon stand beside Hiro; GoGo's hand is solid against his shoulder and Honey's hand is warm in his.

On the bed lays his brother's body, oblivious to the worry in the air.

Two minutes go by with nothing happening. The room's filled with an awkward silence, people pressed together and constantly shifting. Then there's movement, some twitching fingers, then a small turn of the head and everyone stops.

Eyes flutter momentarily before snapping open, staring at the ceiling straight above. After a beat, there's a release of breath. The room's silent when he raises himself up, blearily staring at the crowd of people

Searching for something- for someone.

This time Hiro doesn't look away when silver eyes zero on him.

There's a small smile, a vague reminiscent of Tadashi mixed with a feature that's solely Baymax- old, but completely new because it was all the same and yet different. Whatever angry words were said, none of it seems to matter anymore; the silent exchange sheds away all the guilt and fear, no apology needed. "Hello, Hiro."

And then Hiro's crying and the hiccups are almost too much to control, but that doesn't stop him from smiling back. Uncaring of the multiple eyes watching this private moment, he lunges forward, throwing grace and dignity to the side as he climbs onto the bed.

"Why didn't you tell me, you nerd," he mumbles into the shirt as arms wrap around him.

He shakes as his brother laughs, one that he thought he'd never hear again. "You wouldn't have believed me, knucklehead."

Hiro breathes in the smell that is undoubtedly Tadashi, smiling at the nickname (another thing he didn't think he'd hear again), feeling Honey and GoGo join their hug. Unable to think of anything to properly describe everything that's happened, he says one word into his brother's chest that has him laughing even more.

"Unbelievable."

* * *

 **A/N:** Finally! This one took me a while to write out (even then, my sister had to come in and help). While I had already decided I wanted to write this AU, my sister was the one who suggested Soul!Tadashi/Baymax. Great idea, no?

Am I posting other AU fics rather than finish the ones I already started? Yes. Should I be working on those said fics? Yes. Will I get to them before the next century? Hopefully.

Really, I'm sorry that I haven't finished my Pacific Rim AU. I have a lot of it written down, I swear! I have other AUs I want to do, not to mention the co-authored fic I write with my sister (KiwiRaptor, so check her out!).


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